Kneaders which knead rubber, resin, or the like are conventionally known. For example, Patent Literature 1 discloses an example of a kneader. The kneader disclosed in Patent Literature 1 includes a rotor rotatably arranged in an interior of a chamber formed by a casing and kneads a processed article such as rubber or resin by deforming the processed article so as to tear the processed article apart with a rotation of the rotor.
Since such a kneader is used in a state where large friction is created between the processed article and the rotor as well as an inner surface of the casing, the kneader must withstand abrasion. In particular, when a substance with high hardness such as silica is incorporated into raw material rubber of tires as of late, abrasion becomes more severe. For this reason, constituent members of a kneader are often subjected to chromium plating, spray coating, and the like to impart abrasion resistance.
However, abrasion proceeds during a period of use and a surface treatment layer may become thinner or may peel off. In addition, since contents of operation (hardness of processed raw materials and the like) even differ among machines of a same model, it is difficult to determine a state of wear and tear simply based on operation time. Therefore, when performing equipment maintenance, it is important that such states are inspected.
Conventionally, such inspections involve, for example, opening a door (drop door) provided on a kneader and have an experienced worker visually and manually inspect locations corresponding to check points. Therefore, when including personnel for ensuring safety and time required for machine shutdown and startup, inspections are labor-intensive and time-consuming. In addition, whether or not an inspection is performed is determined based on history and past results of maintenance and an operation status of a machine. If a determination of whether or not such a full-scale inspection is immediately necessary can be made with a simple inspection, an appropriate maintenance plan can be formulated and a reduction in cost can be achieved. Significant advantages may be particularly gained if reduction can be achieved in work associated with inspection and downtime of the machine.
However, since kneaders are structured such that a rotor rotates inside a space called a chamber as described in, for example, Patent Literature 1, an entirety of an interior is not viewable in one glance and an inspection of the interior requires changing viewing directions. Therefore, work accompanying an inspection is difficult.
In addition, for example, according to Patent Literature 2, a casing forming a chamber has a two-piece structure which can be vertically divided. During an inspection, the casing is separated and opened to enable inspection of an interior thereof.
However, according to Patent Literature 2, opening and dividing the casing into two pieces is labor-intensive and time-consuming, and restoration such as assembly of the casing after an inspection is similarly labor-intensive and time-consuming. Therefore, an inspection cannot be readily performed.
Since kneaders are machines subjected to extremely large forces during kneading, such a two-piece structure is unfavorable in terms of strength and requires reinforcement such as increasing wall thickness in order to ensure that strength is comparable to that of an integrated structure which cannot be divided into two pieces. Therefore, such a two-piece structure is also unfavorable in terms of weight and size.